From what I have seen there is a love or hate feeling for Olympic rifles. The first couple I looked at felt lighter built than Armalite or Bushmasters and I did not like that. Yesterday I say an Olympic carbine with A2 stock and I was impressed. It felt as sturdy as my Bushmaster. Actually better. It was very tight and fit well not to mention the color actually matched unlike my multi colored Bushy. The trigger pull was fabulous very light and CRISP again unlike my Bushy that has a bit of gritty creep. Only problem I saw is I did not see any 5.56 stamping to show it would chamber nato ammo without problems. Other comparisons I have are this.Bushmaster says that the uppers are forged and so is the front sight. Inside my carry handle it sure looks like cast marks and the front sight really has alot of marks that look like cast marking. The Olympic was smooth and clean more like what I would expect a forged and machined piece to look like.

Again I am very new to these weapons and have not had a chance to handle many of the various brands.I am trying to learn the in's and out's though. There seams to be so many variables with these weapons.

I have Bushy, Colt, and Armalite ARs and I just bought a preban Oly Arms M4 from a local police officer. My lower has the 5.56 stamp on it. I really love the quality of the lower, however I there is one problem with it. I noticed that it will not accept thermold mags like my other ARs. Also, some of my USGI mags tend to fall out sometimes. Other than that, I love it. Maybe someone can give me some advice on how to fix this because I believe this problem can be solved.

I now have 3 Olys and I really like them. They are highly accurate and very reliable. If it is a gun made in the last few years, it will be a 5.56. The stamping is on the top of the barrel in front of the sight tower. It wil be simply 556 or 556SS if the barrel is stainless.

Just out of curiosity, is there any reason the lower would need to say 5.56? I have a bushmaster upper that is chambered for 5.56, but my Oly lower doesn't say 5.56.
By the way, what would happen if the upper WASNT chambered for 5.56 and you shot 5.56 through it?

Originally Posted By Sparky5:
Other comparisons I have are this.
Bushmaster says that the uppers are forged and so is the front sight. Inside my carry handle it sure looks like cast marks and the front sight really has alot of marks that look like cast marking.
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Those marks are leftover from the forging process as the dies are slammed together (your seeing the seem). This is what FORGED parts are supposed to look like. Bushy doesn't spend the money to grind it all down - it isn't needed and doesn't effect the opearation of the rifle.

The Olympic was smooth and clean more like what I would expect a forged and machined piece to look like.

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No that is what a modern cast piece looks like (i.e. investment casting). They can cast so precise that little (if any) finishing machineing is required.
Yes it usually looks much prettier, but it will be less strong. Is the extra strength really needed? That's for you to decide.
However I don't buy my AR-15s for 'looks' but for functions. And forging is better functionally.

Originally Posted By Sparky5:
Inside my carry handle it sure looks like cast marks and the front sight really has alot of marks that look like cast marking. The Olympic was smooth and clean more like what I would expect a forged and machined piece to look like.

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The rough areas you are describing are the forging seams. These seams, about 1/4" wide, are found on both the receiver forgings and the front sight forging. While most of the seam is normally machined smooth, there will sometimes be visible pits. That's normal (you can also see them on the bodies of many Trijicon ACOGs, for example).
The smooth, narrow seams on the Olympic parts are those of cast parts. Cast parts require minimal machining, and often "look nicer". They also aren't nearly as strong as a forged part, and are not Mil-Spec.
-Troy

Thanks guys. I knew about forged being stronger but being I use many cast parts when I build flintlocks I am used to seeing marks like I see on my Bushmaster. I did not realize forged pieces also looked like this. Guess it is a different beast. Cast parts for flintlocks take lots of work to clean up. Of course they are mostly sand cast the old fashioned way.